In order to clarify the mechanism behind dynamical processes at solid surfaces such as dissociative adsorption and associative desorption of hydrogen, photo-stimulated desorption of adsorbed molecules, quantum transport phenomena, and transient response of surface electron system to ultrashort laser pulses, it is necessary to have an aocurate knowledge of potential energy surfaces, excited as well as the ground states of electron system, and the enterrelation between electronic transitions and state-changes of molecular motion. With this in mind, theoretical studies on dynamical processes at solid surfaces have been done. The obtained results are summarized as follows.1. Making stress on the spatial as well as temporal locality of electronic excitations, we have investigated trajectories of molecules in photo-stimulated desorption. On the basis of the obtained results, dependences of the desorption probability on energy, time duration, and penetration depth of laser pulses are clarifie
… Mored.2. As a dynamical quantum filter, the orientation dependent activation barrier can select rotational states of molecules which attempt to pass through the barrier and to desorb. On the way toward the vacuum from the barrier (transition region), molecules are rotationally excited, de-excited, or retain rotational states at the transition region. It is found that molecules rotationally de-excited as well as those retaining rotational states at the transition region do helicopter-like rotational motion, and that molecules rotationally excited do cartwheel-like rotational motion.3. An expression of time-resolved two-photon photoemission spectrum is derived from a microscopic point of view. On the basis of the obtained results, it is clarified how the information about the lifetime of intermediate states at surfaces can be obtained by the cross correlation trace. Furthermore, the effects of inter-band excitations on the cross correlation trace are clarified.4. The electron correlation effects on electron transport phenomena in an atom-sized contact between an STM-tip and a metal surface are investigated with the aid of the Hubbard Hamiltonian. It is shown that intra-and inter-subband scattering of traveling electrons are induced by Coulomb interacion at finite-temperatures and that the step wise variation of the conductance as a function of the stretching distance of the STM-tip is considerably affected.金属表面近傍に局在する電子状態の超短レーザー光パルスを用いた時間領域分光の理論の定式化を行ったポンプ光によるバルク状態を占める電子の局在状態への移動は,直接過程とバンド間遷移を伴う間接過程からなり,それぞれの過程によって放出される光電子は異なる運動エネルギー分布,異なるポンプ・プローブ遅延時間依存性を示す.特に,この遅延時間依存性の違いから局在状態の寿命などが評価できることを示した.4)STM探針・金属表面間の原子サイズ接合部分での量子輸送現象と電子相関効果表面の微細接合領域の電子系をハバ-ド模型で記述し,量子輸送現象に現れる電子相関効果を調べた.その結果,有限温度では,電子間相互作用によりによりサブバンド内やサブバンド間電子散乱過程が誘起されるため,コンダクタンの量子化が著しく損なわれることを見出した. Less